There are innumerable illnesses and injuries that result in the need for extended bed rest by patients and invalids. Unfortunately, while bed rest is often used to facilitate a patient's recovery from illnesses or injuries, an excessive amount of time spent in bed rest often creates other medical problems. In particular, extended bed rest can result in pressure wounds such as decubitus ulcers or bed sores. The pressure wounds are caused by the reduction in blood flow at a particular point on the patient's body. Usually, this is due to excessive pressure at that point, which is caused by continuous uneven support provided by the mattress or support surface on which the patient is laying. As the blood flow is cut off, bed sores can quickly develop and spread at a rapid pace. If not promptly and properly treated, pressure wounds can even result in a greater injury to a patient than the original illness or injury for which the bed rest was taken. As a result, it would be desirable to have a method of eliminating or reducing the likelihood of pressure wounds when a patient is confined to bed rest.
An early attempt to address this problem was initiated by medical practitioners who would attempt to prevent the occurrence of pressure wounds by physically rotating a patient on the patient's bed on a periodic basis. Due to the shortage of personnel at many medical facilities, or to oversight, manual rotation of patients may not always occur at the proper time. Sometimes, it may not occur at all. As a result, even in a facility where the staff is trained and aware of the problems associated with pressure wounds, patients may not receive adequate care in regard to the avoidance of pressure wounds. It would be desirable to have a method of avoiding the need to rely on human action and to automatically avoid pressure wound injuries caused by constant pressure applied to particular areas of a patient's body.
Support surfaces have been developed for a variety of uses in regard to long-term patient care. A support surface's primary function is to relieve or distribute pressure from many areas of the human body. This is done in a variety of ways using air cells, foam, gel, and other materials to design and construct the support surface. For an air support surface, the best pressure relief results when areas or sections of the support surface are deflated (lowered) allowing for pressure relief, while other areas or sections stay inflated supporting the weight of the body. Support surfaces can be used to provide long-term support for patients or invalids.
A common type of inflatable support surface is an alternating pressure support surface. Support surfaces that utilize alternating pressure are used to prevent and cure pressure wounds such as decubitus ulcers and bed sores. In theory, when a patient is placed on this specialty mattress, only a portion of the patient's body has pressure on it at any given time. This is accomplished by inflating one set of cells while a second set of cells is deflated. The inflated cells support the weight of the body while the deflated cells do not provide pressure on the patient's body. As a result, the deflated cells provide pressure relief and thereby encourage blood flow.
Alternating pressure support surfaces typically use a preset time interval to alternate pressure within the cells. This time interval is typically around five minutes. At the end of the preset time interval, the inflated cells will deflate as the deflated cells inflate. This continually changes the pressure points on the body, allowing blood to flow more freely. The improved blood flow helps to prevent pressure wounds from occurring, and also helps pre-existing wounds to heal.
One difficultly in designing a good pressure-relieving surface is maintaining the definition between the inflated and deflated air cells. It is desirable to avoid tenting and over-depression. Tenting is the tendency of the space above the deflated air cell to be partially covered by the adjacent inflated air cells. The body weight on the inflated air cell tends to flatten it out, and thereby intrude upon the open space left by the deflated air cell. Over-depression of the air cell occurs when a weight is applied to one area, which then is depressed, and the depression naturally also pulls on the adjacent air cell material depressing it also. This results in an excessively large depressed area, and not enough area inflated to properly support the body. One way to overcome these two problems is to have many very small independent air cells.
In addition to bed sores caused by pressure problems, there are also situations where properly controlled temperature levels may be important to a patient's well-being. For example, in certain medical settings, such as the operating rooms, there is a desire not only to have a pressure relieving support surface, but also to assist in the temperature control of the body. There is a need to add heat or cold to the area under or on top of the body. This can greatly aid the physician in controlling correct body temperatures required for certain procedures.
Currently, there are devices that are essentially a blanket through which warm air is passed to heat the body. One such device is known by the trade name Bear Hugger™. However, this device is like a blanket placed over the body and interferes with the access to the patient's body during the operation. In addition, large amounts of heated air are required to maintain the blanket temperature, and the operating room tends to heat up. It would be desirable to have a method of controlling a patient's temperature in these situations without the heat and patient access drawbacks associated with prior art devices.
While attempting to address the basic need to prevent the formation of pressure wounds during the healing process, the prior art has failed to provide an alternating pressure support surface that is capable of preventing tenting and over-depression. In addition, the prior art has not provided an efficient method of controlling temperature in the support surface.